Interface between opto-electronic devices and fibers

ABSTRACT

An interface system includes separate optical and mechanical interfaces between opto-electronic devices and fibers. This allows each of these components to be optimized for there particular function. This also allows two surfaces to be provided for the optical interface, allowing the opto-electronic elements to be spaced further apart than the fibers. The interface system can be integrated together, used in conjunction with a conventional fiber housing, and can be surface mounted with an electrical interface.

CROSS-REFERENCES TO RELATED APPLICATIONS

The present application is related to the commonly assigned, co-pendingU.S. application Ser. No. 09/418,022 entitled “Optical Subassembly”,filed concurrently herewith, the entire contents of which are herebyincorporated by reference for all purposes.

FIELD OF THE INVENTION

The present invention is directed to interfacing opto-electronic deviceswith fibers, particularly using separate elements for an opticalinterface and a mechanical interface.

DESCRIPTION OF RELATED ART

There are numerous ways to couple light to and from opto-electronicdevices and fibers. One typical manner in which this is achieved is tobutt couple the opto-electronic devices right up against the end facesof the fiber. Such butt-coupling requires active alignment to achievedesired levels of coupling efficiency. Further, butt-coupling does notallow the light beam to be modified. Finally, such butt-couplingtypically requires close positioning of the opto-electronic devices inaccordance with the spacing of the fibers, increasing crosstalk.

Another manner of achieving coupling between fibers and opto-electronicdevices is to use short fibers, which in turn are coupled to the fibers.This allows surface emitting opto-electronic devices to be coupled withfibers, but still requires active alignment.

One passive alignment scheme proposed involves providing holes in all ofthe components to be aligned, e.g., a ferrule housing the fibers, alight coupling device including optics and a substrate including theopto-electronic devices. Pins are then inserted into the holes torealize alignment of all the elements. Such single shot alignment maynot be accurate enough for all applications. Further, the materialswhich can be used for the light coupling device are limited when theholes need to be provided therein. Finally, such alignment requires thatthere be a linear relationship among all of the components.

SUMMARY OF THE PRESENT INVENTION

The present invention is therefore directed to an interface whichsubstantially overcomes one or more of the problems due to thelimitations and disadvantages of the related art.

The above and other objects can be realized by providing an interfacesystem between an opto-electronic device and a fiber in a housingincluding an optics block having at least one optical element formedtherein for coupling light between the fiber and the opto-electronicdevice and a mechanical interface, separate from the optics block, atleast part of the mechanical interface being disposed between the opticsblock and the housing, which aligns and mates the housing and the opticsblock.

The opto-electronic device may include at least two opto-electronicdevices including an optical emitter and an optical detector. Theopto-electronic device may include an array of identical opto-electronicdevices. The mechanical interface may surround the optics block. Themechanical interface may be mounted on the optics block. The housing mayinclude holes there through for receiving corresponding pins therein andthe mechanical interface further includes holes for receiving the pins.A spacer block may be provided between the optics block and theopto-electronic device. An alignment plane of the mechanical interfacemay be at an angle to a top surface of the optics block. A reflectivesurface may direct light between the optics block and the mechanicalinterface. The mechanical interface may include an indentation whichreceives the optics block and an extension in the indentation to providevertical spacing between the optics block and the fiber. The at leastone optical element on the optics block may homogenize light.

The optics block and the mechanical interface may be made of differentmaterial. The optics block may be made from one of silicon and glass.The mechanical interface may be opaque at the wavelengths beingtransferred between the fiber and the optics block. The optics block mayinclude visual alignment features for aligning the optics block with themechanical interface. There may be mechanical mating features on theoptics block and corresponding mechanical mating features on themechanical interface for aligning the optics block and the mechanicalinterface.

The above and other objects may be realized by providing a systemincluding a housing having a fiber, an opto-electronic device, an opticsblock having two surfaces, the optics block coupling light between theopto-electronic device and the fiber, and a mechanical interface,separate from the optics block, at least part of the mechanicalinterface being disposed between the optics block and the housing whichaligns and mates the housing and the optics block.

The opto-electronic device may include at least two opto-electronicdevices and the fiber may include at least two fibers. The at least twoopto-electronic devices may be a light source and a light detector. Theat least two opto-electronic devices may include an array of identicalopto-electronic devices. The at least two opto-electronic devices may beseparated from each other in at least one direction by more than the atleast two fibers are separated from one another. The at least twoopto-electronic devices are separated from each other in at least twodirections by more than the at least two fibers are separated from oneanother in each respective direction. The system may be surface mountedto an electrical interface.

A spacer between the optics block and the opto-electronic device maysurround the opto-electronic device. A substrate may be provided withboth a bottom of the opto-electronic device and the spacer being bondedto the substrate. The top surface of the opto-electronic device may bebonded to the spacer and the spacer further includes interconnectiontracks.

These and other objects of the present invention will become morereadily apparent from the detailed description given hereinafter.However, it should be understood that the detailed description andspecific examples, while indicating the preferred embodiments of theinvention, are given by way of illustration only, since various changesand modifications within the spirit and scope of the invention willbecome apparent to those skilled in the art from this detaileddescription.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects, aspects and advantages will bedescribed with reference to the drawings, in which:

FIG. 1A is an exploded elevational perspective view of an interface ofthe present invention in conjunction with the fibers in a housing andthe opto-electronic devices;

FIG. 1B is an elevational perspective view of the system of FIG. 1A;

FIG. 1C is a side view also illustrating internal features of the systemof FIG. 1B;

FIG. 1D is an exploded front view also illustrating internal features ofthe system of FIG. 1B;

FIG. 1E is a top view of the system of FIG. 1B;

FIG. 1F is a front view of the system of FIG. 1B;

FIG. 2A is an exploded elevational perspective view of an opticalsubassembly of the present invention;

FIG. 2B is an exploded side view of FIG. 2A;

FIG. 3A is an exploded perspective view of the fiber housing and aninterface of the present invention;

FIG. 3B is an exploded side view of FIG. 3A;

FIG. 4A is a front view of another embodiment of the optical interfaceof the present invention;

FIG. 4B is top view of the opto-electronic devices in relation toalignment holes;

FIG. 5 is a cross-sectional side view of another embodiment of theinterface of the present invention;

FIG. 6 is a cross-sectional side view of another embodiment of theoptical subassembly of the present invention;

FIG. 7A is an elevational exploded view of another embodiment of theoptical subassembly of the present invention; and

FIG. 7B is an exploded side view of the configuration shown in FIG. 7A.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

As can be seen in FIGS. 1A-1F, a plurality of fibers 10 are insertedinto a ferrule 12. Opto-electronic devices 14 which are to be incommunication with the fibers 10 are preferably provided on a siliconbench or sub-mount 16. In turn, this silicon bench 16 is preferablyprovided on a substrate 18. An optics block 20 provides at least oneoptical element between each opto-electronic device 14 and acorresponding fiber 10. The optics block 20 is preferably spaced fromthe opto-electronic devices 14 by a spacer 15. The optical elementspreferably include elements which collimate, focus and/or homogenize thelight. Since the optics block has two surfaces, two optical elements maybe provided thereon. Further, if required, additional optics blocks maybe bonded to and spaced from the optics block 20 to provide additionalsurfaces.

A mechanical interface 22 aligns the optics block 20, which is alreadyaligned with the optical devices 14 and with the mechanical interface22, with the fibers 10. This may be achieved by alignment features onboth the mechanical interface 22 and the ferrule 12 housing the fibers10. In the particular example shown, these alignment features consist ofholes 24 in the ferrule 12, which are already typically present foraligning the ferrule with other devices, and alignment holes 26 in themechanical interface 22. Once these alignment holes 24, 26 are aligned,an alignment pin, not shown, may then be inserted therein to maintainthe aligned position.

The provision of separate elements to provide the mechanical interfaceand the optical interface provides several advantages. For example, theprovision of the alignment holes 26 in the mechanical interface 22allows the optics block to be made of a material selected for itsoptical properties. For example, the optics block may be made of glass,which is preferable for forming optics therein. However, it is difficultto accurately form cylindrical holes in glass. Thus, this material wouldnot be suitable if the holes had to be provided therein as well, i.e.,if the mechanical and optical interface were to be realized by singleelement. Further, since the mechanical interface is to accept thealignment pins, it must be of sufficient size to accommodate the pins.Glass may be too fragile for such a purpose. Finally, glass is able towithstand the heat such as during soldering of the device to a printedcircuit board or other electrical interface. Thus, the system may besurface mounted or pluggable to an electrical interface.

The mechanical interface may similarly be made of a material best suitedfor its function. The mechanical interface 22 also preferably includesan aperture 28 which allows light to travel between the opto-electronicdevices 14 and the fibers 10 without interference from the mechanicalinterface. This aperture also allows the mechanical interface to be madeof any desired material, such as an opaque, thermally stable material inwhich holes may be accurately and easily formed, such as a glass filledplastic, ceramic or molded plastic, without regard to the opticalproperties thereof.

Further, in the particular example shown, the aperture 28 is made largeenough to surround the optics block 20, except for at a lip 30, which inturn provides the desired separation between a top of the optics block20 and an end face of the fibers. If the mechanical interface 22 is madeof a material which is transparent to wavelengths of light beingexchanged between the fibers and the opto-electronic devices, such anaperture 28 may no longer be needed. Some cut-out for accepting theoptics block 20, with the remaining portion serving as a spacer, maystill be desirable. Either configuration will result in no physicalcontact between the fibers 10 and the optics block 20.

The alignment for the entire structure is discussed below in relation toFIGS. 2A-3. follows. FIGS. 2A-2B, show the alignment of the opticssubassembly including the optics block 20 and the opto-electronicdevices 14. First, the opto-electronic devices 14 are provided on thebench 16. Then, if the spacer 15 is being used, alignment features 34,such as fiducial marks, on the spacer 15 are aligned to alignmentfeatures 32, such as fiducial marks, on the bench 16. The spacer 15 isthen bonded, e.g., using solder or epoxy, into place on the bench 16.The bevels which can be seen on the interior surface of the spacer 15simply arise when using silicon as the spacer and the hole therein isformed by wet etching silicon along its crystalline plane. Whilewet-etching is a simple way of forming the hole in the spacer, verticalside walls may be more advantageous, e.g., for load bearing.Substantially vertical side walls may be realized by dry etchingsilicon. Further, other materials such as ceramic, glass, plastic, maybe used for the spacer 15. If the spacer 15 is transparent towavelengths of interest, the hole therein may not be required.

Then, alignment features 36, such as fiducial marks, on the optics block20 are aligned with the corresponding features on the spacer 15 and thebench 16 to align the optics block to the opto-electronic devices 14.The optics block 20 is then bonded into place, e.g., using solder orepoxy, on the spacer 15. The optical elements on the optics block 20, aswell as the alignment features 36, may be mass-produced on a wafer leveland then diced to form individual optics blocks. Thus, only thealignment of the optical block 20 is required to align all of theoptical elements thereon with the opto-electronic devices 14.

Preferably, the alignment and bonding of the spacer and the optics blockoccur on a wafer level, and then diced to form respective dies which arethen aligned to the bench 16. The alignment of the spacer is not verysensitive, i.e., the spacer just needs to be aligned so that it does notblock light between the optics block 20 and the opto-electronic device.While a spacer may be formed directly on the optics block itself, theuse of a separate spacer 15 allows larger vertical separation to beachieved. The use of a separate spacer is particularly advantageous whenproviding optical elements on a bottom surface of the optics block 20,since the processes for forming the optics and the spacer featuresinterfere with each other. Finally, use of a separate spacer allows thesealing off of the opto-electronic device 14 to be more readily andstably achieved. Such sealing protects the opto-electronic device 14from environmental factors, such as humidity.

For certain wavelengths, e.g., in the near infrared, the optics block 20may be made of another material, e.g., silicon. Then, all of theelements in the optical subassembly, i.e., the substrate, the spacer andthe optics block, may be made of the same material, e.g., silicon.Making all of these elements of the same material reduces stress betweenthese elements due to a difference in the thermal coefficient ofexpansion.

Alignment of the optics block 20 to the mechanical interface 22 and thefibers 10 is shown in FIGS. 3A-3B. While the optics block 20 has alreadybeen aligned with the opto-electronic devices 14, only the optics block20 is shown for simplicity. In the particular example shown, the opticsblock 20 is to be passively aligned with the mechanical interface 22.Access holes 38 are provided in the mechanical interface to facilitatepositioning of the optics block 20. When the mechanical interface is notto surround the optics block, the access holes 38 are not needed.

Such passive alignment may be realized using fiducial marks and/ormechanical mating features on the optics block 20 and the lip 30 of themechanical interface 22. The lip 30 provides an optical mounting surfacewhich maintains the optics block 20 at the desired distance from the endface of the fibers 10. Once aligned, the optics block 20, and thus theopto-electronic devices 14, are bonded to the mechanical interface 22.The mechanical interface 22, and all the components bonded thereto, arealigned to the housing 12 via alignment holes 24, 26 to complete thestructure.

In addition to the passive alignment set forth above, in which alignmentfeatures are provided on the elements being aligned, passive alignmentmay also be realized using an alignment template and/or using theposition of the holes for receiving the pins in the mechanicalinterface. Further, active alignment may also be used.

An alternative embodiment is shown in FIG. 4A. Here, the mechanicalinterface 22 does not surround the optics block, but rather ispositioned on top of the optics block 20. The aperture 28 and thealignment holes 26 are still part of the mechanical interface 22, butthe other features are not needed. Further, the alignment features maybe included on the body of the mechanical interface 22, since the lip isno longer present.

By utilizing both surfaces of the optics block 20, the opto-electronicdevices 14 may be placed further apart, while still realizing a compactsystem for delivering light between the opto-electronic devices 14 andthe fibers 10. Such placement may reduce cross talk between theopto-electronic devices. As shown in FIG. 4A, assuming theopto-electronic devices are light emitters, optics 44 on a first surface42 of the optics block 20 collimates and deflects light from theopto-electronic device 14. Optics 46 on a second surface 48 of theoptics block 20 focuses light onto the fiber 10. Obviously, if theopto-electronic devices are detectors, the functioning of the opticswould be reversed.

The ability to place the opto-electronic devices further apart than thefibers is particularly advantageous when the system is a transceiversystem, i.e., there is at least one light emitter and at least one lightdetector. This spacing may be further enhance by additionally separatingthe emitter and detector in a direction orthogonal to the directionshown in FIG. 4A. Such a configuration is shown in FIG. 4B, where alight emitter 50 is separated from a light detector 52 in twodirections. While these elements are still between the alignment holes24, 26, they are further apart than the fibers 10 and are also separatedan orthogonal direction. Such separation minimizes crosstalk, whilemaintaining the original profile. Further, this separation can berealized even when the optics block is not larger than the mechanicalinterface.

A configuration employing the interface of the present invention wherethe fiber housing is positioned orthogonally to the plane of theopto-electronic devices is shown in FIG. 5. The alignment holes 24, 26are still used to align the fiber housing 12 and the mechanicalinterface 22, the mechanical interface 22 is now aligned to the side ofthe optics block 20. In order to direct light between the fibers and theopto-electronic devices 14, a reflective surface 60 is provided. Asshown in FIG. 5, this reflective surface 60 may be formed in glass orother materials. A metal coating may be provided on this surface toenhance the reflectivity thereof. The material having the reflectivesurface may then be bonded to a top surface of the optical block 20.

In the particular example shown in FIG. 5, the opto-electronic element14 is a VCSEL and another opto-electronic element 14′ is a power monitorfor monitoring the power output by the VCSEL. A first element 62 on theoptics block 20 splits off and collimates part of the beam output by theVCSEL and directs it to the power monitor 14′. A second optical element64 may be provided on the optics block 20 to focus the light onto thepower monitor 14′. Details of such a configuration are set forth incommonly assigned, co-pending U.S. patent application Ser. No.09/386,280 entitled “Diffractive Vertical Cavity Surface Emitting LaserPower Monitor and System” (U.S. Pat. No. 6,314,223) the entire contentsof which are hereby incorporated by reference for all purposes.

Meanwhile, the undeflected portion of the light travels to a thirdoptical element 66, where it is focused onto the fiber, after beingreflected by the reflective surface 60. Thus, in accordance with thepresent invention, alignment may be realized using the alignment holesalready available on the fiber housing without requiring that thecomponents all be in the same plane. While a VCSEL array is discussedabove, a detector array could be similarly positioned.

While all the previous configurations have illustrated theopto-electronic devices bonded on the bottoms thereof to a substrate 16,thereby requiring wire-bonding to realized their required electricalconnections, FIGS. 6-7B illustrate bonding the top of theopto-electronic devices to the optics block. Since all theinterconnections on the typical opto-electronic devices are provided onthe top thereof, such bonding allows the use of wire bonding to beeliminated, which in turn allows more compact interconnections to berealized.

As shown in FIG. 6, the interconnections to the opto-electronic device14 can be realized using a pair of flex leads, a signal flex lead 72 anda ground flex lead 74. An interconnect spacer 70 serves the samefunction as the previous spacer 15, but also includes interconnectiontracks for connecting the opto-electronic element 14 to the signal flexlead 72. If space permits, interconnection tracks for the ground flexlead 74 may also be provided on the interconnect spacer 70. Otherwise,the ground flex lead 74 may be attached to the bottom of theopto-electronic device 14, as shown in FIG. 6. While shown as a separateelement in FIG. 6, the interconnect spacer 70 may be integral with theoptics block 20. The opto-electronic device preferably is mounted on aheat sink block 78. Thus, the module can be surface mounted or pluggedinto an electrical interface, e.g., a printed circuit board or flexcircuit, without additional housing which may be needed to connect thewire bond configurations discussed above.

As shown in FIGS. 7A and 7B, another configuration eliminating the needfor wire bonds includes again providing the interconnect spacer 70 towhich the opto-electronic device 14, here a VCSEL array, is bonded.While shown as a separate element in FIGS. 7A and 7B, the interconnectspacer 70 may be integral with the optics block 20. Instead, ofconnecting the opto-electronic device 14 to flex leads, the interconnectspacer 70 now includes metal lines 80 on a bottom surface thereof,extending from the opto-electronic device 14. A chip carrier 86,preferably ceramic, has a hole 84 therein for receiving theopto-electronic device 14 therein. The chip carrier 86 is preferablyattached to the spacer 80 using a sealing ring 88, e.g., anyconventional adhesive.

The chip carrier 86 also includes a connection region 82 with vias toconnect the metal lines 80 to the outside, e.g., through a bottomsurface of the chip carrier. This may be accomplished, for example,using holes 90 through the chip carrier lined with metal. Thus, themodule can be surface mounted or plugged into an electrical interface,e.g., a printed circuit board or flex circuit, without additionalhousing which may be needed to connect the wire bond configurationsdiscussed above. While the configuration shown in FIGS. 7A and 7B hasassumed all required connections for the opto-electronic device are onthe top surface thereof, a ground connection could also be provided onthe bottom surface.

When using a spacer which is transparent to wavelengths of interest andin the path of the radiation, such as shown in FIGS. 6-7B, the spacermay have optical elements formed thereon. For example, if the spacer andthe optics block are made of the same material, there will not be anoptical interface between them. Thus, a bottom surface of the spacer canbe used on a second optical surface. The opto-electronic device could beslightly removed from this bottom surface even when bonded to the bottomsurface, for example, providing a thick enough layer of bondingmaterial. If a separate spacer is not used, the opto-electronic devicemay still be attached to the bottom of the optics block with thisbonding spacing such that the optics block still provides two surfaces.If the spacer and the optics block are made of different material,optics may be provided on either surface of the spacer. Of course,additional optics block may be bonded together to provide the surfacesneeded, but with a commensurate increase in thickness of the system.

It is further noted that the any of the individual components describedin connection with a particular embodiment may be used with otherconfigurations. For example, the opto-electronic device 14 as shown inFIGS. 6-7B, may be bonded to the bottom of the optics block in theconfiguration of FIGS. 1-2A.

While the present invention is described herein with reference toillustrative embodiments for particular applications, it should beunderstood that the present invention is not limited thereto. Thosehaving ordinary skill in the art and access to the teachings providedherein will recognize additional modifications, applications, andembodiments within the scope thereof and additional fields in which theinvention would be of significant utility without undue experimentation.Thus, the scope of the invention should be determined by appended claimsand their legal equivalents, rather than by examples given.

What is claimed is:
 1. An interface system between an opto-electronicdevice and a fiber in a housing, the housing having a terminal surfaceat which the end face of the fiber is located, the interface systemcomprising: an optics block having at least one optical element formedtherein for coupling light between the end face of the fiber and theopto-electronic device; and a mechanical interface which aligns andmates the housing and the optics block, said mechanical interface beingseparate from the optics block and the housing, wherein at least part ofthe mechanical interface is disposed between the optics block and thehousing, and wherein the mechanical interface includes a first surfaceto be positioned adjacent to the terminal surface of the housing and asecond surface, opposite the first surface, adjacent to the opticsblock.
 2. The interface system of claim 1, wherein said opto-electronicdevice comprises at least two opto-electronic devices comprising anoptical emitter and an optical detector.
 3. The interface system ofclaim 1, wherein said opto-electronic device comprises an array ofidentical opto-electronic devices.
 4. The interface system of claim 1,wherein said mechanical interface surrounds said optics block.
 5. Theinterface system of claim 1, wherein said mechanical interface ismounted on said optics block.
 6. The interface system of claim 1,wherein the housing includes holes there through for receivingcorresponding pins therein and said mechanical interface furthercomprises holes for receiving the pins.
 7. The interface system of claim1, further comprising a spacer block between the optics block and theopto-electronic device.
 8. The interface system of claim 1, wherein analignment plane of the mechanical interface is at an angle to a topsurface of the optics block.
 9. The interface system of claim 8, furthercomprising a reflective surface directing light between the optics blockand the mechanical interface.
 10. The interface system of claim 1,wherein the mechanical interface comprises an indentation which receivesthe optics block and an extension in the indentation to provide verticalspacing between the optics block and the fiber.
 11. The interface systemof claim 1, wherein said at least one optical element on the opticsblock homogenizes light.
 12. The interface system of claim 1, whereinsaid optics block and said mechanical interface are made of differentmaterial.
 13. The interface system of claim 1, wherein said optics blockis made from one of silicon and glass.
 14. The interface system of claim1, wherein said mechanical interface is opaque at the wavelengths beingtransferred between the fiber and the optics block.
 15. The interfacesystem of claim 1, wherein said optics block comprises visual alignmentfeatures for aligning the optics block with the mechanical interface.16. The interface system of claim 1, further comprising mechanicalmating features on the optics block and corresponding mechanical matingfeatures on the mechanical interface for aligning the optics block andthe mechanical interface.
 17. The interface system of claim 1, whereinsaid mechanical interface further comprises mechanical alignmentfeatures to be mated with corresponding mechanical alignment features inthe housing.
 18. The interface system of claim 17, wherein saidmechanical alignment features in the mechanical interface arelongitudinally extending holes, the mechanical alignment features in thehousing are longitudinally extending holes, and the interface systemfurther comprising pins to mate corresponding longitudinally extendingholes.
 19. The interface system of claim 1, wherein the at least oneoptical element is a photolithographically formed optical element. 20.The system of claim 19, wherein said mechanical alignment features inthe mechanical interface are longitudinally extending holes, themechanical alignment features in the housing are longitudinallyextending holes, and the system further comprising pins to matecorresponding longitudinally extending holes.
 21. A system comprising: ahousing having a fiber, the housing including a terminal surface atwhich an end face of the fiber is located; an opto-electronic device; anoptics block having two surfaces, said optics block coupling lightbetween the opto-electronic device and the end face of the fiber; and amechanical interface which aligns and mates the housing and the opticsblock, said mechanical interface being separate from the optics blockand the housing, wherein at least part of the mechanical interface isdisposed between the optics block and the housing, and wherein themechanical interface includes a first surface adjacent to the terminalsurface of the housing and a second surface, opposite the first surface,adjacent to the optics block.
 22. The system of claim 21, wherein saidopto-electronic device comprises at least two opto-electronic devicesand the fiber comprises at least two fibers.
 23. The system of claim 22,wherein said at least two opto-electronic devices comprise a lightsource and a light detector.
 24. The system of claim 22, wherein said atleast two opto-electronic devices comprise an array of identicalopto-electronic devices.
 25. The system of claim 22, wherein said atleast two opto-electronic devices are separated from each other in atleast one direction by more than said at least two fibers are separatedfrom one another.
 26. The system of claim 25, wherein said at least twoopto-electronic devices are separated from each other in at least twodirections by more than said at least two fibers are separated from oneanother in each respective direction.
 27. The system of claim 21,further comprising a spacer surrounding the opto-electronic device. 28.The system of claim 27, further comprising a substrate, both a bottom ofsaid opto-electronic device and the spacer being bonded to thesubstrate.
 29. The system of claim 27, wherein a top surface of saidopto-electronic device is bonded to the spacer and the spacer furthercomprises interconnection tracks.
 30. The system of claim 21, whereinthe system is surface mounted to an electrical interface.
 31. The systemof claim 21, wherein said mechanical interface further comprisesmechanical alignment features, the housing includes mechanical alignmentfeatures, and the system further comprising pins to mate correspondingmechanical alignment features.
 32. The system of claim 21, wherein theoptics block includes a photolithographically formed optical element.